One important figure of merit of a switching converter is load regulation, where it is desirable to have tight regulation over the entire load range. A switching converter (switching regulator) can be operated in a continuous mode or discontinuous mode depending on whether the current through the inductor decreases to zero during the switching cycle. As is well known to those skilled in the art, in continuous mode, the output voltage is independent of the load and is given by the formula:                BuckVo=Vi(δ)  (1)        Boost        
                    Vo        =                  Vi                      1            -            δ                                              (        2        )            
δ=Duty Cycle
Thus, the load regulation for a converter in continuous mode is very good. In fact, as shown by equations 1 and 2, the voltage regulation for a switching mode converter in continuous mode should be zero because of the output voltage is independent of the load although, in actual converters, there is still some small drop in the output voltage with increasing load due to parasitics.
In discontinuous mode, the output current is not large enough to keep the inductor current from going to zero during the cycle. A DC/DC switching converter operating in discontinuous mode has a smaller duty cycle for the same input and output voltage than one operating in continuous mode. This difference in duty cycle definition is what causes the output voltage to be larger in discontinuous mode and the load regulation to suffer. In converters having an error amplifier, the gain of the error amplifier allows the converter to operate with little change in output voltage during discontinuous mode. Utilizing an error amplifier in the design of a switching converter complicates the design of the controller because it must be compensated for changes in load and temperature. In addition, an error amplifier dramatically increases the current drain for the control circuit of the switching converter. Therefore, in small battery powered devices it is desirable to have a converter which does not require an error amplifier. In such converters, the output is compared directly to a ramp and therefore the output voltage has to change more dramatically in order to change the duty cycle. The greater the voltage difference between the output voltage and the ramp voltage, the more the converters will suffer from poor load regulation. Two factors that play a predominant role in determining at what load a converter transitions between discontinuous mode and continuous mode is the switching frequency and inductor size. Once these parameters are specified, the designer of the controller has no control over how wide of a load range places the converter in discontinuous mode and therefore is unable to avoid a large load regulation.